Mozilla has released Firefox 7. Unlike releases of Firefox 5 and Firefox 6 which were relatively minor upgrades to the browser, Firefox 7 includes a number of significant improvements, most important of which is probably the drastically reduced memory usage.

I really don't use FF much anymore, but I did a test (12 tabs) and the new version dropped from 350MB to 250MB memory usage. Not too shabby!

I'd also like to note that my Chrome is using 150MB but also has a 36MB render process for each tab I have open (18, non with flash) and six worker processes using 20MB each. Total 918MB!

This is not a scientific comparison by any means since the tabs are not the same on each, but they are all just non flash web pages. Even with all that memory being used, chrome's UI still responds faster that FF's.